This contract provides NIEHS/NTP with a wide variety of collaborative pathology services that best support NTP's evolving toxicologic research and chemical/agent testing mission. The services provided range from traditional GLP-compliant toxicologic pathology support and the conduct of the Pathology Working Groups to the development and/or refinement of special pathology-based procedures and innovative technologies responsive to investigative research concerns and mechanistic issues. Because the NTP's service needs are largely unpredictable, adequate numbers of NTP-qualified and experienced pathologists, proficient technical personnel and support staff must be committed on an as-needed basis to be immediately responsive to the collective pathology requirements of eight individual task assignments, including several involving client-site services.